CA2257072A1 - Method and apparatus for reliably producing pacing pulse trains - Google Patents
Method and apparatus for reliably producing pacing pulse trains Download PDFInfo
- Publication number
- CA2257072A1 CA2257072A1 CA002257072A CA2257072A CA2257072A1 CA 2257072 A1 CA2257072 A1 CA 2257072A1 CA 002257072 A CA002257072 A CA 002257072A CA 2257072 A CA2257072 A CA 2257072A CA 2257072 A1 CA2257072 A1 CA 2257072A1
- Authority
- CA
- Canada
- Prior art keywords
- capacitor
- control circuit
- pulse
- capacitors
- sequencer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/18—Applying electric currents by contact electrodes
- A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
- A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
- A61N1/362—Heart stimulators
- A61N1/37—Monitoring; Protecting
- A61N1/3706—Pacemaker parameters
- A61N1/3708—Pacemaker parameters for power depletion
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61N—ELECTROTHERAPY; MAGNETOTHERAPY; RADIATION THERAPY; ULTRASOUND THERAPY
- A61N1/00—Electrotherapy; Circuits therefor
- A61N1/18—Applying electric currents by contact electrodes
- A61N1/32—Applying electric currents by contact electrodes alternating or intermittent currents
- A61N1/36—Applying electric currents by contact electrodes alternating or intermittent currents for stimulation
- A61N1/362—Heart stimulators
- A61N1/3621—Heart stimulators for treating or preventing abnormally high heart rate
- A61N1/3622—Heart stimulators for treating or preventing abnormally high heart rate comprising two or more electrodes co-operating with different heart regions
Abstract
A method and apparatus for reliably producing a pulse train include a control system which automatically selects a secondary pulse generator circuit when high frequency pulses are needed or whenever the use of alternating pulse generators would be desirable. This secondary pulse generator may be provided for other functions or it may be dedicated to providing alternate pulses, for example, to increase the frequency of the primary pulse generator without the loss of amplitude. This system may be useful for many purposes including implementing a noninvasive programmed stimulation operation or for providing antitachycardia arrhythmia therapy.
Description
CA 022~7072 1998-12-01 W O98/10833 PCT~US97/16213 Description Mf~th~-d ~n~ ratus for Reliably Producir~ Pacir~ l.c.~ Tr~in.c Technir.~l FiPl~
The invention relates to cardiac pacemakers, and more particularly to cardiac p~ce-m~kers which are capable of reliably delivering pacing pulse trains of desired amplitude.
Back~rolmfl Art Implanted cardiac p~cem~k~rs are employed to assist patients suffering from severe bradycardia or chronotropic incompetence. A cardiac p~cem~k~r captures the heart by delivering an electrical pulse to the myocardium of a selected heart chamber during an interval in the cardiac cycle in which the cardiac tissue is excitable. These electrical pulses cause depolarization of cardiac cells and con.cequ~ntly, contraction in the chamber, provided that the energy of the pacing pulse as delivered to the myocardium exceeds the threshold value.
P~c.em~k~r.s may have a pre-defined pacing rate or pre-defined range of pacing rates. Other par~m~k~.rs may be rate responsive or rate adaptive in which case the pacing rate may be adjusted based on sensed physiological pa~ el~s. For example, when the patient is undergoing emotional or physical stress, the pacing rate may be increased to acc-~mm-~d~te the enh~n~.ed biological dem~n~l~
The delivery of fast bursts of pacing pulses may be used for antitachycardia therapy or non-invasive programmed stiml-l~tion ("NIPS"). In antitachycardia therapy, a fast burst of pacing pulses 2 o can be used to capture a certain region of the heart in order to t~ lilldl~ an arrhythmia. In non-invasive programmed stim~ tion, a fast burst of pacing pulses may be generated in a clinical setting to produce a tachycardia ~llhyLl~ ia for diagnostic pu.~,oses.
Delivery of such fast bursts of pacing pulses imposes a tremendous burden on the voltage multiplication and regulation circuits used to charge tank capacitors in typical pacemakers. This 2 5 burden often makes it difficult to produce trains of closely separated pacing pulses with consistently high output amplitude. This burden is further i"~l~,ased as the internal impedance of the pacemaker ~ battery increases with increased battery depletion.
When producing high frequency pulse trains, the tank capacitor from which the energy is delivered must be ,ech~lged fast enough between pulses to ensure that all the pulses in the train have 3 o consistently high output amplitude. This is necessary to ensure that the desired stimlll~tion of the heart muscle is achieved.
CA 022~7072 1998-12-01 Generating high frequency bursts, however, is problematic for typical pacern~k~rs~ and this is especially so for those ~ecign~d to treat bradyarrhythmias. One reason for this is that the internal impedance of a typical lithium-iodide pae~ k~r battery is relatively high even when it is new. As the battery is depleted, its internal impedance increases to the point where the end of battery life is reached. In typical batteries the internal impedance of the battery may run from hundreds of ohms initially to hundreds of kiloohms near the end of battery life.
As a result of increasing battery imperl~n~e, the amount of charge that can be drawn within a given amount of time by the pacemaker's circuitry from the battery to fully recharge the tank capacitor decreases. Eventually, with s~lfflri~ntly il~ ased battery impedance and sufficiently high pulse frequency, not enough charge can be drawn from the battery to fully recharge the tank capacitor. As a result, the amplitude of pulses in the pulse train may be reduced beyond the point where reliable stim-ll~tion of heart muscle is achieved. Thus, the p.,.rollllance of the high frequency pacing therapy may be reduced or completely mitig~t~
Con~i~t~ntly m~int~ining the desired pulse amplitude may be a problem at normal pacing rates when battery impedance is excessive. The same pulse amplitude problems that occur at higher frequency can occur at lower frequencies because the battery impedance may be high enough that complete recharge of the tank capacitor can not be accomplished in the available time period for recharge.
If the amplitude of the pacing pulses is sufficiently (limini.ch~d, it is possible that the pacing 2 0 pulses will not capture the heart muscle. This could have severe effects on the patient.
Therefore, it would be highly desirable to provide a system which enables pulses to be reliably produced with consistently a~ iate amplitude.
Disclosure of Invention The present invention relates to an implantable pa~Pmqk~r that is capable of reliably producing pulse trains of conxiC~e~ly a~ o~liate ~ plilllde. The pacemaker uses two pulse generators which operate in alternate cycles to allow recharging of each pulse generator tank capacitor while the other tank capacitor is being discharged. In this way a pulse is provided alternately by each of the pulse g~l,el~tol~. The tank capacitor of each pulse gellel~Lur therefore has effectively almost twice the recharge time. As a result, even when the impedance of the battery is 3 o sllhxt~nti~lly increased as a result of the approach of end of battery life, pulses of consistently high voltage amplitude may be produced because of the additional time available to recharge the capacitors.
In many i"~ nrec, it is advantageous to provide an additional pulse generator to implement the present invention. However, there are some in.~t~nl~es where at least two pulse generators are CA 022~7072 1998-12-01 already used. In such cases, the second pulse generator would not conventionally have been used to produce the pulse trains. For example, in a dual chamber stim~ tor, one of a pair of pulse generators may provide ventricular stimlll~tion while the other provides atrial stimlll~tion. In accolddllce with the present invention, the second pulse generator may be co-opted into providing alternate pulses when necessary.
Where two pulse generating systems are utilized to provide pulse trains that m~int:~in the desired pulse amplitude, it is advantageous to have a way to ~lltom~ti~ y enable the cycling between the first and second pulse generators on alternate cycles. Whenever nf.ce~ry, the pacemaker includes circuitry to perform ~ ol.".lic source toggling between the primary tank capacitor and an additional tank cal)~ci~ol for gell~ldlil.g successive pacing pulses in the train. In this way, while one of the capacitors is being used to deliver a pacing pulse, the other is being recharged.
Brief Description of the Drawin~s Figure 1 is a block diagram of an embodiment of a pacem~k~r according to the invention;
and Figure 2 is a circuit diagram of an embodiment of a pulse generator for reliably producing trains that m~int~in a desired pulse amplitude.
Best Mode for Carryi~ Out th~ Tnventi-ln The preferred embodiment of the invention will now be described with ~~r~l~nce to the accompanying figures. Like numerals will be used to dPsign~te like parts throughout.
2 0 Referring now to Figure 1, an implantable pacem~ker, generally Ae.~ien~t~d 10, is illustrated in srhPm~ti~ fashion with connection to the human heart 12. The present invention is applicable to pacemakers with atrial sensing, ventricular sensing, ventricular pacing and atrial pacing or any combination thereof. In addition, the features of the invention could also be combined with an i..lpldl.L~ble defibrillator/cardioverter.
With this undel~L~-di--g, the illustrated pa~ern~k~r 10 cul--l lises a microprocessor 14 which executes various control plO~ldlllS to regulate the action of the pacem~k~r. The microprocessor 14 may be connected to additional memory 16 which stores programs and data as needed.
Conventionally, one or more internal clocks may be provided to permit timing of various events.
For example, an A-V interval timer 18 may be provided. Similarly, a V-A interval timer 20 may 3 o also be provided as known in the art.
The microprocessor may also be provided with a telemetry circuit 22 to enable colllllllll~ir~lion by the antenna 24 with an external pac~ornqk~r programmer (not shown). Telemetry permits an ~ttenrling physician to obtain data and hlfol...~Lion from the pac~ k~r and to control the pac.eTn~ker by setting various selectable parameters.
CA 022~7072 1998-12-01 W O 98/10833 PCT~US97/16213 The invention is amenable to imple~..e~,ti.lion with p~t~ern~kers using either bipolar or unipolar leads. The illustrated pacPm~k~.r 10 may be connected to the heart 12 through a first lead 26 to an electrode 27 in the atrium and through a second lead 30 to an electrode 31 in the ventricle 32. An indirr~itlll electrode (e.g. the pal~çm~kPr can) is provided to cc,l,lpl~,t~, the electrical circuit through the body. In the illustrated embodiment, a can 43 or outer casing of the p~cem~ker serves as the indirre~ electrode.
Atrial electrogra~n sensing, through an atrial sense circuit 34, and ven~ric~ r sensing through a ventricular sense circuit 36, provide hlrollllation to the microprocessor 14 cul1c~ ~illg the condition and le~ul1siveness of the heart. In addition, pacing pulses are provided to the ventricle and/or the 1 0 atrium from the atrial/ventricular stim~ c generator 38. However, it is clearly with the scope of those skilled in the art to provide cardioversion/defibrillation capabilities in response to the detected condition of the heart.
Stimulation of the heart is passed through coupling capacitors 40 and 41 in a conventional fashion. The switches 73 and 74 and resistors 75 and 76 may be used to actively discharge the coupling capacitors 40 and 41.
To control the pulse rate of the ventricular stim~ c gen~l~Lol 38, the microprocessor may acquire information on the condition of the heart through an il.~edd,lce circuit 42. The impedance circuit 42 detects changes in i~ edallce primarily due to the rl~ g shape of the heart, which may be related to the physical shape of the heart as it beats and pumps blood. This hlfollllaLion can be 2 0 used to derive a measure of the stroke volume or ejection fraction or end diastolic volume of the heart. FUILhC1I11~)1e~ the shape of the illll,eddl~ce waveform can provide further ill~llllalion on other cardiac timing parameters such as isovolumetric contraction time or pre-ejection period. One exemplary impedance circuit is described in U.S. Patent No. 5,531,772 to Prutchi.
In addition to the measurement of impedance, a sensor 44 may also be provided to obtain 2 5 an indication of physiologic need and adjust the pacing rate. Such a sensor may be an accelelolllcle., as described by Dahl, U.S. Patent No. 4, 140,132, a tcll~peIaLule sensor as described Alt, U.S.
Patent No. 4,688,573, or any other suitable sensor parameter which may be correlated to physiological need of the patient.
The atrial/ventricular stimulus gcnclaLol 38, shown in Figure 2, includes a battery 56 3 0 connected to a pair of regulators 58 and 60. The regulator 60 is connected to a tank capacitor 62 while the regulator 58 is connected to a tank capacitor 64. The regulators 58 and 60 include multiplication and regulation circuitry used to charge the tank capacitors 62 and 64.
The tank capacitor 64 is connectable by a switch 66 to a node 70 while the regulator 60 is connected by a switch 68 to the same node 70, which co~ ect~ via the lead 30 to the ventricle 32 of CA 022~7072 1998-12-01 the heart 12. The tank capacitor 64 is also connl~ctqhle via the switch 67 and the lead 26 to the atrium 28 of the heart 12.
The pace seq~lenrer 72 controls the ~wi~;hes 66, 67 and 68 to utilize the regulator 58 and tank capacitor 64 to ~llgmPnt the pulses produced by the regulator 60 and tank capacitor 62 when needed. In particular with the switch 66 open and the switch 68 closed, a normal pacing pulse may be produced by the tank capacitor 62 to ventricle 32.
At the same time with switch 67 closed, a pulse train may be delivered via the lead 26 to the atrium 28. After each pulse is created, and L~ lçd to the heart tissue 12, the switches 67 and 68 may be opened allowing the cqrqritorS 62 and 64 to be lechdl~ed by the regulators 58 and 60 and 1 0 battery 56.
When it is desired to 2ugm~nt the ventricular pacing pulse train, the switch 67 is opened and the switches 66 and 68 may be alternately opened and closed at a desired frequency by the pace sequenrer 72. This allows additional time for the capacitors 62 and 64 to be recharged. Namely, while the capacitor 64 is being discharged to produce a pacing pulse, the capacitor 62 may be lt;char~ g and vice versa.
The pace seq-l~nrer 72 may be a state mq~llinP which is programmed to provide switching sequences. The seq~lenrer 72 is connected for control by the microprocessor 14. However, a variety of other conventional techni-lues may be used to control the switches 66,67,68,73 and 74.
With the present invention it is possible to produce a normal pulse frequency through the 2 0 regulator 60 and capaciLor 62 and then when select~d~ produce a higher frequency pulse train without concern for loss of reliability. Because of the extra time provided for recharging of the tank capacitors 62 and 64, the possibility of incomplete charging is lessened and therefore the likelihood that pulses of full amplitude will be produced is increased.
As one example of the application of the present invention, the regulator 60 and capacitor 62 can produce normal frequency pacing pulses. When it is desired to undergo a noninvasive programmed stimlllqtion cycle, one or more bursts of high frequency pulses may be produced for ventricular analysis and (liqgn( .stir ~ oses. This may be done by alternately producing pulses using regulator 60 and cqpq~it()r 62 and the regulator 58 and capacitor 64. This stimnl~tion cycle can be implernr.nted through telemetry by the physician. A signal received by the antenna 24 and telemetry 3 o circuit 22 may be passed to the micro~.oces~or 14 which in turn sends an appru~liate control signal to the sequencer 72. In the same way the stimlllqtion may be terminated when suffirirnt data has been obtained.
Similarly, it may be desirable to counteract a detected tachycardia arrhythmia by producing a high frequency burst cycle. A tach~dllllyLllll~ia is detected by the atrial sensor circuit 34 or the W O 98/10833 PCT~US97n6213 ventricular sense circuit 36. The ll~ic,ol rocessor 14 then signals the pace seq ~en~.er 72 to implement a high frequency burst cycle to the ventricle using both tank capacitors 62 and 64. Once the arrhythmia has been countered, the pace se~ r 72 may ~ ~lo,~ ir~lly revert to a norrnal pacing frequency.
In accor-l~nce with still another embodiment of the present invention, tank rap""itoTs 62 and 64 are used to produce a combined pulse train when low battery c~n~ io" is d~te~.t~d by the conventional monitor 80 or low pulse amplitude has been detected by a monitor 82. That is, upon detection of a low battery or low pulse amplitude, the llli~aul,loc~ ol 14 directs an ~,opliate control signal to the sequenrer 72 to operate switches 66 and 67 to co-opt the regulator 58 and tank capacitor 64 to produce alternate pulses of a pulse train supplied to the lead 30.
The invention relates to cardiac pacemakers, and more particularly to cardiac p~ce-m~kers which are capable of reliably delivering pacing pulse trains of desired amplitude.
Back~rolmfl Art Implanted cardiac p~cem~k~rs are employed to assist patients suffering from severe bradycardia or chronotropic incompetence. A cardiac p~cem~k~r captures the heart by delivering an electrical pulse to the myocardium of a selected heart chamber during an interval in the cardiac cycle in which the cardiac tissue is excitable. These electrical pulses cause depolarization of cardiac cells and con.cequ~ntly, contraction in the chamber, provided that the energy of the pacing pulse as delivered to the myocardium exceeds the threshold value.
P~c.em~k~r.s may have a pre-defined pacing rate or pre-defined range of pacing rates. Other par~m~k~.rs may be rate responsive or rate adaptive in which case the pacing rate may be adjusted based on sensed physiological pa~ el~s. For example, when the patient is undergoing emotional or physical stress, the pacing rate may be increased to acc-~mm-~d~te the enh~n~.ed biological dem~n~l~
The delivery of fast bursts of pacing pulses may be used for antitachycardia therapy or non-invasive programmed stiml-l~tion ("NIPS"). In antitachycardia therapy, a fast burst of pacing pulses 2 o can be used to capture a certain region of the heart in order to t~ lilldl~ an arrhythmia. In non-invasive programmed stim~ tion, a fast burst of pacing pulses may be generated in a clinical setting to produce a tachycardia ~llhyLl~ ia for diagnostic pu.~,oses.
Delivery of such fast bursts of pacing pulses imposes a tremendous burden on the voltage multiplication and regulation circuits used to charge tank capacitors in typical pacemakers. This 2 5 burden often makes it difficult to produce trains of closely separated pacing pulses with consistently high output amplitude. This burden is further i"~l~,ased as the internal impedance of the pacemaker ~ battery increases with increased battery depletion.
When producing high frequency pulse trains, the tank capacitor from which the energy is delivered must be ,ech~lged fast enough between pulses to ensure that all the pulses in the train have 3 o consistently high output amplitude. This is necessary to ensure that the desired stimlll~tion of the heart muscle is achieved.
CA 022~7072 1998-12-01 Generating high frequency bursts, however, is problematic for typical pacern~k~rs~ and this is especially so for those ~ecign~d to treat bradyarrhythmias. One reason for this is that the internal impedance of a typical lithium-iodide pae~ k~r battery is relatively high even when it is new. As the battery is depleted, its internal impedance increases to the point where the end of battery life is reached. In typical batteries the internal impedance of the battery may run from hundreds of ohms initially to hundreds of kiloohms near the end of battery life.
As a result of increasing battery imperl~n~e, the amount of charge that can be drawn within a given amount of time by the pacemaker's circuitry from the battery to fully recharge the tank capacitor decreases. Eventually, with s~lfflri~ntly il~ ased battery impedance and sufficiently high pulse frequency, not enough charge can be drawn from the battery to fully recharge the tank capacitor. As a result, the amplitude of pulses in the pulse train may be reduced beyond the point where reliable stim-ll~tion of heart muscle is achieved. Thus, the p.,.rollllance of the high frequency pacing therapy may be reduced or completely mitig~t~
Con~i~t~ntly m~int~ining the desired pulse amplitude may be a problem at normal pacing rates when battery impedance is excessive. The same pulse amplitude problems that occur at higher frequency can occur at lower frequencies because the battery impedance may be high enough that complete recharge of the tank capacitor can not be accomplished in the available time period for recharge.
If the amplitude of the pacing pulses is sufficiently (limini.ch~d, it is possible that the pacing 2 0 pulses will not capture the heart muscle. This could have severe effects on the patient.
Therefore, it would be highly desirable to provide a system which enables pulses to be reliably produced with consistently a~ iate amplitude.
Disclosure of Invention The present invention relates to an implantable pa~Pmqk~r that is capable of reliably producing pulse trains of conxiC~e~ly a~ o~liate ~ plilllde. The pacemaker uses two pulse generators which operate in alternate cycles to allow recharging of each pulse generator tank capacitor while the other tank capacitor is being discharged. In this way a pulse is provided alternately by each of the pulse g~l,el~tol~. The tank capacitor of each pulse gellel~Lur therefore has effectively almost twice the recharge time. As a result, even when the impedance of the battery is 3 o sllhxt~nti~lly increased as a result of the approach of end of battery life, pulses of consistently high voltage amplitude may be produced because of the additional time available to recharge the capacitors.
In many i"~ nrec, it is advantageous to provide an additional pulse generator to implement the present invention. However, there are some in.~t~nl~es where at least two pulse generators are CA 022~7072 1998-12-01 already used. In such cases, the second pulse generator would not conventionally have been used to produce the pulse trains. For example, in a dual chamber stim~ tor, one of a pair of pulse generators may provide ventricular stimlll~tion while the other provides atrial stimlll~tion. In accolddllce with the present invention, the second pulse generator may be co-opted into providing alternate pulses when necessary.
Where two pulse generating systems are utilized to provide pulse trains that m~int:~in the desired pulse amplitude, it is advantageous to have a way to ~lltom~ti~ y enable the cycling between the first and second pulse generators on alternate cycles. Whenever nf.ce~ry, the pacemaker includes circuitry to perform ~ ol.".lic source toggling between the primary tank capacitor and an additional tank cal)~ci~ol for gell~ldlil.g successive pacing pulses in the train. In this way, while one of the capacitors is being used to deliver a pacing pulse, the other is being recharged.
Brief Description of the Drawin~s Figure 1 is a block diagram of an embodiment of a pacem~k~r according to the invention;
and Figure 2 is a circuit diagram of an embodiment of a pulse generator for reliably producing trains that m~int~in a desired pulse amplitude.
Best Mode for Carryi~ Out th~ Tnventi-ln The preferred embodiment of the invention will now be described with ~~r~l~nce to the accompanying figures. Like numerals will be used to dPsign~te like parts throughout.
2 0 Referring now to Figure 1, an implantable pacem~ker, generally Ae.~ien~t~d 10, is illustrated in srhPm~ti~ fashion with connection to the human heart 12. The present invention is applicable to pacemakers with atrial sensing, ventricular sensing, ventricular pacing and atrial pacing or any combination thereof. In addition, the features of the invention could also be combined with an i..lpldl.L~ble defibrillator/cardioverter.
With this undel~L~-di--g, the illustrated pa~ern~k~r 10 cul--l lises a microprocessor 14 which executes various control plO~ldlllS to regulate the action of the pacem~k~r. The microprocessor 14 may be connected to additional memory 16 which stores programs and data as needed.
Conventionally, one or more internal clocks may be provided to permit timing of various events.
For example, an A-V interval timer 18 may be provided. Similarly, a V-A interval timer 20 may 3 o also be provided as known in the art.
The microprocessor may also be provided with a telemetry circuit 22 to enable colllllllll~ir~lion by the antenna 24 with an external pac~ornqk~r programmer (not shown). Telemetry permits an ~ttenrling physician to obtain data and hlfol...~Lion from the pac~ k~r and to control the pac.eTn~ker by setting various selectable parameters.
CA 022~7072 1998-12-01 W O 98/10833 PCT~US97/16213 The invention is amenable to imple~..e~,ti.lion with p~t~ern~kers using either bipolar or unipolar leads. The illustrated pacPm~k~.r 10 may be connected to the heart 12 through a first lead 26 to an electrode 27 in the atrium and through a second lead 30 to an electrode 31 in the ventricle 32. An indirr~itlll electrode (e.g. the pal~çm~kPr can) is provided to cc,l,lpl~,t~, the electrical circuit through the body. In the illustrated embodiment, a can 43 or outer casing of the p~cem~ker serves as the indirre~ electrode.
Atrial electrogra~n sensing, through an atrial sense circuit 34, and ven~ric~ r sensing through a ventricular sense circuit 36, provide hlrollllation to the microprocessor 14 cul1c~ ~illg the condition and le~ul1siveness of the heart. In addition, pacing pulses are provided to the ventricle and/or the 1 0 atrium from the atrial/ventricular stim~ c generator 38. However, it is clearly with the scope of those skilled in the art to provide cardioversion/defibrillation capabilities in response to the detected condition of the heart.
Stimulation of the heart is passed through coupling capacitors 40 and 41 in a conventional fashion. The switches 73 and 74 and resistors 75 and 76 may be used to actively discharge the coupling capacitors 40 and 41.
To control the pulse rate of the ventricular stim~ c gen~l~Lol 38, the microprocessor may acquire information on the condition of the heart through an il.~edd,lce circuit 42. The impedance circuit 42 detects changes in i~ edallce primarily due to the rl~ g shape of the heart, which may be related to the physical shape of the heart as it beats and pumps blood. This hlfollllaLion can be 2 0 used to derive a measure of the stroke volume or ejection fraction or end diastolic volume of the heart. FUILhC1I11~)1e~ the shape of the illll,eddl~ce waveform can provide further ill~llllalion on other cardiac timing parameters such as isovolumetric contraction time or pre-ejection period. One exemplary impedance circuit is described in U.S. Patent No. 5,531,772 to Prutchi.
In addition to the measurement of impedance, a sensor 44 may also be provided to obtain 2 5 an indication of physiologic need and adjust the pacing rate. Such a sensor may be an accelelolllcle., as described by Dahl, U.S. Patent No. 4, 140,132, a tcll~peIaLule sensor as described Alt, U.S.
Patent No. 4,688,573, or any other suitable sensor parameter which may be correlated to physiological need of the patient.
The atrial/ventricular stimulus gcnclaLol 38, shown in Figure 2, includes a battery 56 3 0 connected to a pair of regulators 58 and 60. The regulator 60 is connected to a tank capacitor 62 while the regulator 58 is connected to a tank capacitor 64. The regulators 58 and 60 include multiplication and regulation circuitry used to charge the tank capacitors 62 and 64.
The tank capacitor 64 is connectable by a switch 66 to a node 70 while the regulator 60 is connected by a switch 68 to the same node 70, which co~ ect~ via the lead 30 to the ventricle 32 of CA 022~7072 1998-12-01 the heart 12. The tank capacitor 64 is also connl~ctqhle via the switch 67 and the lead 26 to the atrium 28 of the heart 12.
The pace seq~lenrer 72 controls the ~wi~;hes 66, 67 and 68 to utilize the regulator 58 and tank capacitor 64 to ~llgmPnt the pulses produced by the regulator 60 and tank capacitor 62 when needed. In particular with the switch 66 open and the switch 68 closed, a normal pacing pulse may be produced by the tank capacitor 62 to ventricle 32.
At the same time with switch 67 closed, a pulse train may be delivered via the lead 26 to the atrium 28. After each pulse is created, and L~ lçd to the heart tissue 12, the switches 67 and 68 may be opened allowing the cqrqritorS 62 and 64 to be lechdl~ed by the regulators 58 and 60 and 1 0 battery 56.
When it is desired to 2ugm~nt the ventricular pacing pulse train, the switch 67 is opened and the switches 66 and 68 may be alternately opened and closed at a desired frequency by the pace sequenrer 72. This allows additional time for the capacitors 62 and 64 to be recharged. Namely, while the capacitor 64 is being discharged to produce a pacing pulse, the capacitor 62 may be lt;char~ g and vice versa.
The pace seq-l~nrer 72 may be a state mq~llinP which is programmed to provide switching sequences. The seq~lenrer 72 is connected for control by the microprocessor 14. However, a variety of other conventional techni-lues may be used to control the switches 66,67,68,73 and 74.
With the present invention it is possible to produce a normal pulse frequency through the 2 0 regulator 60 and capaciLor 62 and then when select~d~ produce a higher frequency pulse train without concern for loss of reliability. Because of the extra time provided for recharging of the tank capacitors 62 and 64, the possibility of incomplete charging is lessened and therefore the likelihood that pulses of full amplitude will be produced is increased.
As one example of the application of the present invention, the regulator 60 and capacitor 62 can produce normal frequency pacing pulses. When it is desired to undergo a noninvasive programmed stimlllqtion cycle, one or more bursts of high frequency pulses may be produced for ventricular analysis and (liqgn( .stir ~ oses. This may be done by alternately producing pulses using regulator 60 and cqpq~it()r 62 and the regulator 58 and capacitor 64. This stimnl~tion cycle can be implernr.nted through telemetry by the physician. A signal received by the antenna 24 and telemetry 3 o circuit 22 may be passed to the micro~.oces~or 14 which in turn sends an appru~liate control signal to the sequencer 72. In the same way the stimlllqtion may be terminated when suffirirnt data has been obtained.
Similarly, it may be desirable to counteract a detected tachycardia arrhythmia by producing a high frequency burst cycle. A tach~dllllyLllll~ia is detected by the atrial sensor circuit 34 or the W O 98/10833 PCT~US97n6213 ventricular sense circuit 36. The ll~ic,ol rocessor 14 then signals the pace seq ~en~.er 72 to implement a high frequency burst cycle to the ventricle using both tank capacitors 62 and 64. Once the arrhythmia has been countered, the pace se~ r 72 may ~ ~lo,~ ir~lly revert to a norrnal pacing frequency.
In accor-l~nce with still another embodiment of the present invention, tank rap""itoTs 62 and 64 are used to produce a combined pulse train when low battery c~n~ io" is d~te~.t~d by the conventional monitor 80 or low pulse amplitude has been detected by a monitor 82. That is, upon detection of a low battery or low pulse amplitude, the llli~aul,loc~ ol 14 directs an ~,opliate control signal to the sequenrer 72 to operate switches 66 and 67 to co-opt the regulator 58 and tank capacitor 64 to produce alternate pulses of a pulse train supplied to the lead 30.
Claims (9)
1. A cardiac stimulation apparatus (10) for a patient whose heart needs cardiac therapy comprising:
a capacitor charging circuit (58, 60);
a first capacitor (62) electrically connected to said capacitor charging circuit for providing a pacing pulse;
characterized by a second capacitor (64) electrically connected to said capacitor charging circuit for providing a pacing pulse; and a control circuit (14) for enabling at least one of said capacitors to be charged and discharged, said control circuit connected to a sequencer (72) for enabling said first and second capacitors to be charged and discharged in alternate cycles to produce a pulse train formed by pulses from said first and second capacitors.
a capacitor charging circuit (58, 60);
a first capacitor (62) electrically connected to said capacitor charging circuit for providing a pacing pulse;
characterized by a second capacitor (64) electrically connected to said capacitor charging circuit for providing a pacing pulse; and a control circuit (14) for enabling at least one of said capacitors to be charged and discharged, said control circuit connected to a sequencer (72) for enabling said first and second capacitors to be charged and discharged in alternate cycles to produce a pulse train formed by pulses from said first and second capacitors.
2. The apparatus of claim 1 further comprising means (66, 68) for connecting both of said capacitors to the ventricle.
3. The apparatus of claim 1 including a detector connected to said control circuit for detecting battery end of life conditions, said sequencer (72) being activated by said control circuit when battery end of life conditions are detected.
4. The apparatus of claim 1 wherein said sequencer (72) is activated by said control circuit to produce higher frequency pulse trains at a selected voltage than could be created using only said first capacitor.
5. The apparatus of claim 1 wherein said capacitor charging circuit further comprises a first capacitor charging circuit (60) for charging said first capacitor (68) and a second capacitor charging circuit (58) for charging said second capacitor (64).
6. The apparatus of claim 5 further comprising means (68) for connecting said first capacitor to the ventricle and means (67) for connecting said second capacitor to the atrium, and wherein said sequencer further comprises a first switched connection between said first and second capacitors and a second switched connection between said second capacitor and means for connecting said second capacitor to the atrium.
7. The apparatus of claim 1 including means for detecting tachycardia arrhythmia connected to said control circuit, said control circuit activating said sequencer (72) in response to the detection of a tachycardia arrhythmia.
8. The apparatus of claim 1, including a telemetry device (22) connected to said control circuit for receiving a signal for activating said sequencer.
9. The apparatus of claim 1 further comprising means (42, 44) for detecting a predetermined condition and wherein said control circuit, in response to said means for detecting a condition, causes said second capacitor to produce alternate pulses with said first capacitor.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/714388 | 1996-09-16 | ||
| US08/714,388 US5735880A (en) | 1996-09-16 | 1996-09-16 | Method and apparatus for reliably producing pacing pulse trains |
| PCT/US1997/016213 WO1998010833A1 (en) | 1996-09-16 | 1997-09-16 | Method and apparatus for reliably producing pacing pulse trains |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2257072A1 true CA2257072A1 (en) | 1998-03-19 |
Family
ID=24869843
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002257072A Abandoned CA2257072A1 (en) | 1996-09-16 | 1997-09-16 | Method and apparatus for reliably producing pacing pulse trains |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5735880A (en) |
| EP (1) | EP0927063A1 (en) |
| CA (1) | CA2257072A1 (en) |
| WO (1) | WO1998010833A1 (en) |
Families Citing this family (20)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6324425B1 (en) * | 1999-07-28 | 2001-11-27 | Medtronic, Inc., | Recharge circuitry for multi-site stimulation of body tissue |
| US6879988B2 (en) * | 2000-03-09 | 2005-04-12 | Pkware | System and method for manipulating and managing computer archive files |
| US20020095197A1 (en) * | 2000-07-11 | 2002-07-18 | Lardo Albert C. | Application of photochemotherapy for the treatment of cardiac arrhythmias |
| FR2820640B1 (en) * | 2001-02-09 | 2004-05-14 | Ela Medical Sa | ACTIVE IMPLANTABLE MEDICAL DEVICE, IN PARTICULAR CARDIAC STIMULATOR, DEFIBRILLATOR AND / OR CARDIOVERTER OR MULTI-SITE DEVICE, WITH CYCLE-TO-CYCLE CAPTURE TEST |
| US6625488B2 (en) * | 2001-03-13 | 2003-09-23 | Pacesetter, Inc. | Implantable cardiac stimulation device having a programmable reconfigurable sequencer |
| US6847843B1 (en) | 2001-06-06 | 2005-01-25 | Pacesetter, Inc. | Method and apparatus for electrophysiological testing in an implantable device |
| EP1578266B1 (en) * | 2002-12-12 | 2015-04-29 | Biocontrol Medical (B.C.M.) Ltd. | Efficient dynamic stimulation in an implanted device |
| US7389140B1 (en) * | 2004-06-16 | 2008-06-17 | Kroll Mark W | Adjustment of stimulation current path |
| US9168383B2 (en) * | 2005-10-14 | 2015-10-27 | Pacesetter, Inc. | Leadless cardiac pacemaker with conducted communication |
| US8457742B2 (en) | 2005-10-14 | 2013-06-04 | Nanostim, Inc. | Leadless cardiac pacemaker system for usage in combination with an implantable cardioverter-defibrillator |
| US8527068B2 (en) | 2009-02-02 | 2013-09-03 | Nanostim, Inc. | Leadless cardiac pacemaker with secondary fixation capability |
| WO2012051237A1 (en) | 2010-10-12 | 2012-04-19 | Nanostim, Inc. | Temperature sensor for a leadless cardiac pacemaker |
| US9060692B2 (en) | 2010-10-12 | 2015-06-23 | Pacesetter, Inc. | Temperature sensor for a leadless cardiac pacemaker |
| JP2013540022A (en) | 2010-10-13 | 2013-10-31 | ナノスティム・インコーポレイテッド | Leadless cardiac pacemaker with screw anti-rotation element |
| US9132275B2 (en) | 2010-11-18 | 2015-09-15 | Cardiac Pacemakers, Inc. | Automatic determination of chronotropic incompetence using atrial pacing at rest |
| EP3090779B1 (en) | 2010-12-13 | 2017-11-08 | Pacesetter, Inc. | Pacemaker retrieval systems |
| EP2651494B1 (en) | 2010-12-13 | 2017-02-15 | Pacesetter, Inc. | Delivery catheter |
| EP2654889B1 (en) | 2010-12-20 | 2017-03-01 | Pacesetter, Inc. | Leadless pacemaker with radial fixation mechanism |
| US9511236B2 (en) | 2011-11-04 | 2016-12-06 | Pacesetter, Inc. | Leadless cardiac pacemaker with integral battery and redundant welds |
| WO2014022661A1 (en) | 2012-08-01 | 2014-02-06 | Nanostim, Inc. | Biostimulator circuit with flying cell |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3518997A (en) * | 1969-01-17 | 1970-07-07 | Robert W Sessions | Electronic heart stimulator |
| DE2216193A1 (en) * | 1972-04-04 | 1973-10-11 | Siemens Ag | PACEMAKER |
| US3845773A (en) * | 1972-07-07 | 1974-11-05 | Ass Rech Et D Entraide Cardiol | Cardiac stimulators |
| US4031899A (en) * | 1976-01-22 | 1977-06-28 | Vitatron Medical B.V. | Long life cardiac pacer with switching power delivery means and method of alternately delivering power to respective circuit portions of a stimulus delivery system |
| US4345604A (en) * | 1976-01-22 | 1982-08-24 | Vitafin N.V. | Long life cardiac pacer with switching power |
| US4140132A (en) * | 1978-03-23 | 1979-02-20 | Dahl Joseph D | Variable rate timer for a cardiac pacemaker |
| DE3419439C1 (en) * | 1984-05-24 | 1985-11-21 | Eckhard Dr. 8000 München Alt | Frequency-dependent pacemaker depending on the load |
| US4998974A (en) * | 1990-01-05 | 1991-03-12 | Telectronics Pacing Systems, Inc. | Apparatus and method for antitachycardia pacing in dual chamber arrhythmia control system |
| US5076272A (en) * | 1990-06-15 | 1991-12-31 | Telectronics Pacing Systems, Inc. | Autocontrollable pacemaker with alarm |
| US5163427A (en) * | 1990-11-14 | 1992-11-17 | Medtronic, Inc. | Apparatus for delivering single and multiple cardioversion and defibrillation pulses |
| US5178140A (en) * | 1991-09-05 | 1993-01-12 | Telectronics Pacing Systems, Inc. | Implantable medical devices employing capacitive control of high voltage switches |
| US5360435A (en) * | 1993-02-19 | 1994-11-01 | Medtronic, Inc. | Multiple pulse cardioversion or defibrillation |
| US5531772A (en) * | 1994-11-18 | 1996-07-02 | Intermedics, Inc. | Rate responsive cardiac pacemaker with filtered impedance sensing and method |
-
1996
- 1996-09-16 US US08/714,388 patent/US5735880A/en not_active Expired - Lifetime
-
1997
- 1997-09-16 CA CA002257072A patent/CA2257072A1/en not_active Abandoned
- 1997-09-16 EP EP97941057A patent/EP0927063A1/en not_active Withdrawn
- 1997-09-16 WO PCT/US1997/016213 patent/WO1998010833A1/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| WO1998010833A1 (en) | 1998-03-19 |
| EP0927063A1 (en) | 1999-07-07 |
| US5735880A (en) | 1998-04-07 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0550713B1 (en) | Post-extrasystolic potentiation stimulation with physiologic sensor feedback | |
| US7328067B2 (en) | Cardiac rhythm management system and method | |
| US5735880A (en) | Method and apparatus for reliably producing pacing pulse trains | |
| US6757563B2 (en) | Cardiac rhythm management system with ultrasound for autocapture or other applications | |
| EP0341297B1 (en) | Sensing margin detectors for implantable electromedical devices | |
| US5713930A (en) | Dual chamber pacing system and method with control of AV interval | |
| US8321036B2 (en) | Cardiac rhythm management device | |
| US5713935A (en) | Method and apparatus for monitored biphasic cardiac impedance sensing | |
| AU656420B2 (en) | Method and apparatus for wide area antitachycardia pacing | |
| US20090088813A1 (en) | Cardiac Rhythm Management Device | |
| WO2003059446A1 (en) | Chamber pacemaker system for simultanous bi-chamber pacing and sensing | |
| WO2003089056A1 (en) | Cardiac resynchronisation with adaptive a1-a2 and/or v1-v2 intervals | |
| US6839592B2 (en) | Cardiac resynchronization with adaptive A1-A2 and/or V1-V2 intervals | |
| AU6474586A (en) | Myocardial contractility-sensitive pacer and method | |
| EP1499385A1 (en) | Ventricular safety pacing in biventricular pacing | |
| US5713931A (en) | Method and apparatus for detecting amplitude loss in cardiac pacing pulses |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued |